Fused drop-out cutout



Oct. 19, 1954 D. c. HUBBARD ETAL FUSED DROP-OUT CUTOUT Filed on. 27, 1952 2 Sheets-Sheet l INVENTOS.

Oct 19, 1954 D. c. HUBBARD ETAL FUSED DROP-OUT CUTOUT 2 Sheets-Sheet 2 Filed Oct. 27, 1952 Patented Oct. 19, 1954 FUSED DROP-OUT CUTOUT David 0. Hubbard and William L. Hollander,

Centralia, Mo., assignors to A. B. Chance Company, Centralia, Mo., a corporation of Missouri Application October 27, 1952, Serial No. 317,044

10 Claims.

closed at the top and open at the bottom and so constructed that the lower contact of the fuse tube is ejected from the bottom contact of the circuit, so that the fuse tube will hang with its opening downward before and after operation, thus protecting the fiber liner of the fuse tube from all adverse weather conditions.

Another object of the invention is the provision of an improved fuse drop-out cut-out in which the actual parting of the lower contacts upon rupture of the fuse link is delayed until after the arc has been extinguished inside the fuse tube.

Another object is the provision of an improved device of the class described in which the ejector arm travels over a predetermined are before unlatching the lower contact so that the actual mechanical opening of the circuit will be delayed until the arc has been definitely extinguished within the fuse tube.

Another object is the provision of an improved device of the class described in which there is a wiping contact between the contacts on the fuse tube and those on the support so that the contacts may be kept in good condition and so that the wiping contact at the lower contact of the fuse tube may be used during the unlatching of the fuse to assist in delaying the mechanical opening of the circuit until the arc has been extinguished within the tube.

A further object of the invention is the provision of an improved drop-out fuse construction in which the jet action from the opening at the lower end of the fuse tube reacts with the upper trunnion to produce a torque that tends to swing the lower end of the fuse tube inward toward its contact to hold the lower contact in engaged position during the blast of the are so as to delay the mechanical opening until the arc has been extinguished.

Another object of the invention is the provision of an improved construction for devices of the class described in the form of the resilient spring supported contacts and the provision of stops which protect the springs during jet action to prevent the straining of the springs and to cause 2 the forces to react in such manner that the top trunnion of the fuse tube is also held in closed position during the violent jet action from the lower end of the fuse tube.

Another object of the invention is the provision of an improved ejector construction adapted to pull the fuse link from the fuse tube quickly at all times, even though the rupturing currents are too light to generate sui'licient gases within the fiber tube to eject the link rapidly, thus assuring the extinguishment of the arc in a minimum time.

Another object of the invention is the provision of an improved fuse tube drop-out cut-out, the parts of which are protected from the weather at all times, and which is also adapted to be operated in a conventional way as a disconnect by permitting the manual disengagement of the upper contacts by merely pulling outward on this end of the tube, leaving the tube supported by its lower contacts, and indicating that it has been manually operated as a disconnect.

Another object of the invention is the provision of an improved fuse construction which is adapted to be re-fused and operated in accordance with conventional procedure so that the operators will already be familiar with the mode of handling the device.

Another object of theinvention is the provision of an improved fuse drop-out cut-out which is trip-free, even during the manual closing of the circuit so that, when the fuse tube unit is beingconnected with its contacts, the operator cannot force the closing of the circuit during the existence of an overload; but while the operator is swinging the upper contact into closed position and holding it, the device may nevertheless open at the bottom contact automatically, if a short circuit exists at that time.

Another object of the invention is the provision of an improved fuse tube unit which is provided with means for guiding and diverting the molten elements and the major force of the blast which takes place on fusing, away from the operator, so as to provide limited, but effective, protection for the operator, and particularly for his face.

Another object is the provision of an improved device of the class described having a mechanism that is unaffected by accumulations of ice, and which is adequately protected from such accumulations as may occur.

Another object of the invention is the provision of a device of the class described which gives a visual indication in the open position whether the device has been operated automatically, indicating the existence of a fault, or whether the device has been opened manually, indicating the purposeful de-energizing of the circuit for repairs or other reasons.

Another object is the provision of an improved contact structure which is self-aligning with relation to the trunnions on the fuse tube unit, and the provision of stops and buffers to arrest the reaction that is due to the jet action and to prevent overstressing the contact springs.

Another object is the provision of an improved fuse tube unit and support therefor, which is so constructed that the forcible closing of the contacts by slamming the fuse tube into position, tends to force the ejector arm against the bottom of the fuse tube, rather than to cause the arm to place additional tension on the fuse link element, thus eliminating the shocks that are imparted to the fragile fuse link in the devices of the prior art.

Another object of the invention is the provision of an improved ejector mechanism for the fuse leader, in which the cable is so arranged that it does not slide over the end of the ejector lever as the lever moves, thus reducing, or substantially eliminating, the friction which would be caused by such a sliding action, andwhich would resist the ejector lever operation.

Another object is the provision of improved contact arrangements by means of which the contact fixtures on the fuse tube unit are resiliently urged into engagement with the fixed contact arms, and by means of which the contacts are self-aligning with respect to the trunnions on the fuse tube unit, and by means of which the longitudinal pressure on the fuse tube, which sometimes causes bending after a long period of time, is substantially eliminated.

Another object is the provision of improved arrangements for holding the fuse tube unit against swinging and against return of its lower end into engagement with the lower contact arm after the fuse has blown, the lower end has been released, and the fuse tube unit has swung down at its lower end into a vertical position.

Another object of the invention is the provision of an improved upper contact arm construction which may be provided with a pry-out lever to facilitate the removal of the tube from the upper contact arm.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings accompanying this specification,

Fig. 1 is a side elevational view in partial section, showing a fused drop-out cut-out embodying the invention, with the parts in the position which they assume when it has been provided with a fuse and the fuse unit is supported by the upper and lower contact arms in the closed circuit position;

Fig. 2 is a similar view of a modification in which the fuse tube unit has been provided with a pry-out lever;

Fig. 3 is a fragmentary front elevational view of the upper part of the fuse tube unit;

Fig. 4 is a fragmentary sectional view, taken on the plane of the line 44 of Fig. 1, looking in the direction of the arrows.

Referring to Fig. 1, indicates in its entirety the fuse drop-out cut-out assembly, which preferably includes a supporting structure II and a fuse tube unit l2 carried thereby. The supporting structure H may be embodied in the single insulator type shown in Fig. 1 or it may be carried by two insulators in the manner shown in the prior application of David C. Hubbard, Ser. No. 11,076, filed February 26, 1948, Fuse Drop- Out Cut-Outs, now U. S. Patent No. 2,584,586, dated February 5, 1952.

The single insulator type of Fig. 1 has a porcelain insulator l3, which is formed with a multiplicity of peripherally extending skirts l4 separated by grooves 15; and the insulator preferably has a reduced cylindrical portion l6 adjacent at its middle and additional reduced cylindrical portions l1 and I8 at each end. The middle cylindrical portion 16 of the insulator is surrounded by a metal band IS, the ends of which are provided with two laterally projecting attaching flanges, having a screw bolt 22 passing through them and clamping them together.

One of the attaching flanges has a side extension 23 provided with an aperture for receiving another screw bolt 24, which passes through the attaching flange 25 of an offset bracket 26, securing it to the clamping band [9. The offset bracket 26 has its body 21 extending at right angles to the attaching flange 25 and has another attaching flange 28 extending at an obtuse angle to the body 21.

The attaching flange 28 is secured to the supporting flange 29 of a cross arm clamping member 30 by means of a screw bolt 31. The cross arm clamping member 30 is adapted to engage one side of a cross arm, the other side being engaged by a clamping plate 32; and the two clamping members 30 and 32 are drawn together by longer screw bolts 33, 34 passing through suitable apertures in the cross arm.

Thus the insulator I3 is adapted to be supported from a horizontal cross arm in a tilted position so that the fuse tube unit [2 will extend diagonally upward and away from the cross arm in such manner that whenever the fuse tube unit hangs only from the upper contact arms, it hangs in a vertical position by gravity. By reason of this position of the insulator and fuse tube unit, the fuse tube unit is so supported that it may pivot upon either the upper trunnion or the lower trunnions by gravity to a position which it will retain by gravity.

The reduced cylindrical portions l1 and I8 at each end of the insulator [3 are bordered by one of the insulator skirts [4 on one side and a radially projecting rib 35 on the other side, forming a groove for receiving the clamping bands 36 or 31 of the upper and lower contact supporting arms 38, 39. These contact supporting arms comprise elongated narrow straps of sheet metal, each having a partially cylindrical portion 36 or 31, which embraces the insulator, and each having a pair of parallel, laterally projecting portions 4i, 42 for supporting the spring contacts.

In some embodiments of the invention the contact supporting arms 38, 39 may have their ends embedded and cemented in sockets in the insulator.

The projecting attaching flanges 42 of the band 31 are provided with a pair of apertures for receiving the screw bolts 43 and 44, which pass through both flanges and through the supporting flange 45 of a lower contact fixture 46, having a hood or partial housing 41 for supporting the lower contact trunnions and for enclosing the ejector mechanism and contact mechanism and protecting it from rain. snow, and other adverse weather conditions,

The lower fixture 46 may consist of a. cast metal member proyided with a relatively flat attaching flange 45, and with an aperture 48 for passing a connector bolt 49, which is apertured below its elongated, head 59: for receiving a conductor that is clamped in a groove 5| by a nut on the shank of they bolt, which pulls the head against the conductor.

A similar connector 49 is carried by an up wardly projecting flange 52 carried by the upper contact flxture 53. The hood 4? has parallel side walls 54-, 55- (Fig. 5), a curved top wall 56, a. flat rear wall 5'.'-',. and a flat depending wall 58 (Fig. 1.), leaving the bottom open between the side walls 54, when the fixture is installed properly, as in Fig.1.

The side walls 54. are provided with laterally projecting cylindrical lugs 59, (ill, Fig- 4, having threaded apertures 5| for receiving a pair of cylindrical trunions 62, 63' (Fig. 4).. The trunnions are threaded at their outer ends and engaged in the threaded bore filfwhere they are secured by means of spring washers 54 and lock nuts. 65.

The inner ends 56, 6 of the trunnions. are spaced from each other sufiiciently to pass: the relatively flat flange portions of an ejector arm 63 (Fig. 1), which is pivotally mounted on the tube unit I2.

The hood 4.? supports a leaf spring 6.9, which extends along the inside of itsv top wall 56, and which is initially spaced from the top wall, being tensioned when bent upward, as shown in Fig. 1. This leaf spring 59 passes through an aperture in the rear wall 5? and is secured to a horizontal flange it by means of a screw bolt H. Spring t9 urges the contact portions of the fuse. tube unit 12 resiliently against the trunnions 62, 63..

The fuse tube unit i2 comprises an insulating tube I2, preferably having an outer portion 13, which is adapted to resist exposure to weather, and an inner portion is, which is adapted to resist burning by the heat generated in the melting of the fuse, these two portions being integrally cemented together to form a singlev tube.

At its lower end the. fuse tube "t2 supports the contact fixture 15, which has an upwardly open tubular member 16 for receiving the lower end of the fuse tube. The fuse tube is fixedly secured in the ferrule 75 of the lower fixture by a pair of rivet pins ll, which pass through the ferrule and are riveted therein at such a point that the rivets ll also pass. through grooves in the side of the fuse tube 12.

The fuse tube terminates at 78, inside the blast chute 79, and is open at its lower end, where it is constantly protected from the weather by hanging downward. The lower fixture T5 supports the integralblast chute '59, which has a pair of parallel side walls Be, a top wall 8|. flush with the end 18 of the tube, and a diagonally extending rear wall 32, which extends over toward the center of the tube l2 and is adapted to deflect the gases downwardly and toward the right, away from the face of the operator.

In some embodiments of the invention the blast chute may be eliminated; and the insulating tube 72 may project downwardly past the lower contact fixture 15', being open for the discharge of gases.

The lower fixture T5 is formed with an integral ring 8 located on its upper side, in Fig. 1, for reception of the laterally projecting operating pin 6' of a disconnect. stick upon which the fuse unit it is hung when. it. is: to;- be installed. Lower fixture 15 also has an integral substantially cylindrical body portion 85. below the ring: 84, and provided with a cylindrical bore 86 for receiving an ejector spring 81.

The ejector spring comprises a helical. coil spring reacting at its right end on the end of the bore 86, and engaging at its left end the washer 88 of a suitable ejector strut 8.9. Ejector strut 89 comprises a stiff strut of metal, having. a reduced end 90, which passes through an aperture in themetallic washer 88; and having at its other end 91 a V groove or fork for engaging. on both sides of the ejector lever 68 at its right. edge. Thus the; ejector-spring 81; urges the, ejector lever 53 toward the left in Fig. 1 by means of the strut 89.

The. upper wall of the cylindrical formation is extended toward the left to form a part of a roof 92., which curves upwardly under the top wall 56 of the hood to make sure that the hood; overlaps and drains on the lower fixture 15 at a point where the water will not run into the mechanism..

Referring tov Fig. 5, the laterally projecting portion as of the lower fixture. i5 is provided with a rectangular slot 94'. open toward the left, and adapted to receive. the pivot flange 95 of the. ejector lever 58., which is. pivoted on the rivet 9.6. The rivet 9.5., which forms the. pivot for the ejector lever, also has a laterally projecting cylindrical portion 911 (Fig. 5), about which the cable. leader 98. may be wrapped when the fuse is. installed in the fuse unit 12.

Lower contact fixture '15 also has a. laterally projecting cylindrical threaded stud 99 provided with a knurled thumb nut 1.60, which is adapted to clamp the end of the fuse leader 9.8 after it has been passed about the. threaded stud 99.

The present fuse units I12. are adapted to receive standard fuses, each of which has a circular button at the top. adapted to be clamped against an end surface on the upper fixture ISM by means of the internally threaded cap 12. The. fusible.- portion of the fuse is. located in the upper end of the tube 1-2 and is connected to the stranded copper wire leader cable wire 88, which extends downwardly out of the lower end of. the tube '12 and out of the blast chute 1'9.

Fuse leader 98 passes around the end I93 of the ejector lever 58. and is located in a groove HM in thev bottom or end of ejector lever 68. From the groove 5 54 the leader 98: passes about the stud ill (Fig. 5) and its end is passed about the stud 99. and clamped by the thumb nut. 199. When the fuse leader is so installed, the ejector lever 68 is tensioned; that is, it is moved to. the position of Fig. 1, compressing the spring 8?, and causing the fuse ejector lever 68 to place a tension on the fuse leader 98.

The ejector lever (-38 is pivoted in the slot 94 between the parallel portion m5 of the lower fixture 15; and ejector lever 58 has a relatively flat body flange 106., which is relatively thin, but which is reinforced by a thicker border flange The oval aperture H18 (Fig. 1 in the ejector lever flange I65 is merely for convenience in machining adjacent surfaces, comprising the flat inner surface I59 and the cylindrical end surface IHl on a pair of laterally projecting guide flanges Ill.

These guide flanges, which are. on both sides of the ejector lever E8. also have downwardly extending lips H2, with a diagonally extending face H3 for guiding the trunnions 62, 63 into proper position. The lateral thickness of the reinforcing border flange II is such that it passes between the ends 65, 67 of the trunnions which are carried by the hood 41.

The laterally projecting body 93 of the lower fixture I has each of its side webs I05 provided with the laterally projecting curved contact members II4. These arcuate contact members have lower partially cylindrical surfaces II5 for engaging the trunnions 62, 63, against which they are urged by the spring 69, which bears on the top of the lateral extension 93 at the flange 92 (Fig. 1).

The side webs I05 of the lower contact fixture '15 are extended toward the left, in Fig. 2, to form the curved camming surfaces I I6, which engage the spring 69 in the installation of the fuse tube unit I2 and urge the fixed contacts I I4 into proper engaging position with the trunnions 62, B3.

The ejector lever 68 is also preferably provided with a pair of laterally projecting hammer flanges II I, which are beveled at H8 on the lower left corner to provide a sharp edge at H9. The sharp edge H9 is so located that it is adapted to pass above the curved upper surface of each trunnion B2, 53 so that the trunnions will be struck by the beveled surfaces H8, one of which is located on each side of the ejector lever.

Thus the ejector lever has a cam H8, which is forced over the fixed trunnions to lift the fuse tube unit until the overhang of contact H4 rises above the trunnions. At the same time the impact urges contact H4 off the trunnions.

Referring to the upper contact supporting arm 38 (Fig. 1), here the parallel attaching flanges 4| are made longer than the flanges 42 at the bottom arm 39 for the reason that the upper arm fixture 53 is shorter; and it is desired to support the tube I2 substantially parallel to the insulator I3. Bolt 43 clamps the band 36 on insulator I3.

Two additional screw bolts I20 and I2I pass through both the flanges 4I adjacent their ends and also through an attaching flange I22 of the contact arm fixture 53 to secure this fixture to the upper arm 38. The fixture 53 pivots on the bolt I2I by reason of the clearance provided by an enlarged aperture I23 in attaching flange I22 surrounding the bolt I20. This pivotal movement provides a predetermined amount of adjustment of the jaws of the upper fixture 53 to accord variations in length of the fuse tube unit I2 and still bring the upper trunnions I24 into good contact engagement with the upper fixed contacts.

The upper contact fixture 53 on arm 38 has a rearwardly extending horizontal flange I25 provided with a threaded bore for receiving screw bolt I26, which passes through the end of a leaf spring I21 and secures it to the flange I25. The other end of leaf spring I21 engages a rotatable sleeve I28 carried by a bolt 129, which is secured in apertures in the flanges 4I4I.

The rotatable sleeve I28 is located between the flanges 4I-4I and serves as a roller for engaging leaf spring I2I with a minimum amount of friction. The leaf spring initially extends downwardly at its left end (Fig. 1), but is bent upwardly by engagement with the roller I28, which gives it an initial tension and urges the upper contact fixture 53 in a clockwise direction on its pivot bolt I2I.

The upper contact fixture 53 may comprise a cast metal member; and it is preferably formed with a housing having a pair of parallel side walls I30 integrally joined to a curved top wall I3I and a depending straight back wall I32, forming a hood which is open at the bottom for receiving the upper end of the fuse tube unit I2 and for protecting the contacts and upper mechanism from snow, rain, and other weather conditions.

In some embodiments of the invention the top wall of the upper contact fixture may be omitted; and the upper end of the fuse tube unit made open to discharge gases in particularly large capacity units.

The upper contact fixture I M on the fuse tube unit I2 has a cylindrical body I33 with a cylindrical bore for receiving the fuse tube I2, which is again secured in place by a plurality of rivet pins I34 in a manner similar to the pins IT at the lower end. The cylindrical body I33 has a reduced cylindrical extension I35, which is threaded externally to receive the internal threads of the cap I02, which is closed at its upper end.

There is a bore I31 extending through the fixture IN and registering with the bore I38 in fuse tube I2 for receiving the fuse and its leader. At the upper right corner of the cylindrical portion I33 (Fig. 2) the cylindrical body I33 is provided with a pair of laterally projecting cylindrical trunnions I24; and these trunnions I24 form the upper contacts carried by fuse tube unit I2.

At its lower end the cylindrical body I 33 of the upper contact fixture IOI has a partially cylindrical extension I40, which carries a laterally projecting operating ring I4I. This ring has an aperture I42 like the ring 84 of suflicient size to pass the head on the laterally projecting pin of a disconnect stick, by means of which the fuse tube unit I2 may be manipulated.

Ring MI is used for operating the unit as a disconnect by merely pulling out and disconnecting the upper contact, while the unit I2 pivots on the lower trunnions. Ring MI is also used in the installation of the fuse tube unit to swing the unit upward from a depending position to that of Fig. 1.

The parallel side walls I30 of the upper contact fixture are spaced sufficiently to receive the trunnions I24, which extend laterally from one side wall IN to the other side wall IOI. Above the trunnions I24 the side walls IOI may again have inner walls I43, which are spaced sufficiently to pass the cap I02, but which terminate in lower shoulders I44 located above the trunnions I24. In other words, the side walls of fixture 53 are thickened at I43.

The lateral shoulders I44 are formed with upwardly curved shoulders I45 above the trunnion I24 in Fig. 1 for retaining the trunnion I24 in the fixture 53. Trunnion engaging shoulders I44 extend upwardly and toward the right (Fig. 1) and curve upwardly at I46 to provide a camming surface for engaging the trumiions I 24 to cam the fixture 53 upward until the trunnions I24 pass in the hood and behind the retaining shoulders I45.

The retaining shoulders I45 constitute the fixed contacts for engaging trunnions I24. The relatively thick parallel walls I43 of fixture 53 have outwardly flaring guide surfaces I41 at the right end (Fig. l) for engaging the cap I02 and guiding 9 it in between the walls 143. The fixture 53g1has its attaching flange I22 provided with threaded bores for receiving the screw bolts I48 .(Fig. 1) which secure the left end of the leaf spring 149 to the fixture 53.

This leaf spring extends upwardly and is formed with a hump 5i! engaging the trunnions I24 and urging them against the fixed contacts I45, when the parts are in the position of Fig. 1. The right end of leaf spring M9 is bent downwardly and has its end portion I51 engaging a laterally projecting flange I52 carried by each of the side walls I130. Such a leaf spring its is provided on each side of the fixture adjacent each side wall 139 for engaging each -.trunni on.

The leaf spring 145 may also be tilized for holding the blown fuse unit 12 in the alposition and for preventing it from swin us back and forth in the wind, which might a cidentally result in an accidental engagement of the lower contact with the lowernxture. For this purp se the trunnions 124 may each be provided with flat surface at I53 (Fig. 1), which'flatly engages thespring M9 in the depending position to keep the fuse tube unit from swinging.

Another mode of preventing the swinging of the fuse tube unit is to provide a spring 154, which has a partially cylindrical portion 155 hooked over the bolt ['20 and has its rear end 156 under the roller 128. From the bolt 1126 this spring 15.4 extends diagonally downward at 1.51 under the depending Wall 132, where it :iS bent upward to provide a resilient end portion .158 that engages the side of the cap the position of Fig. 1 and engages the top of the cap. Thus When the fuse is blown and the unit 12 swingsdown from the position of Fig. 1 to the vertical position, the spri 154 will thereafter ten to keep it from swinging on its upper pivots.

Operation Themede of manipulation and mode of operation of the mechanismis as follows: A fuse with its leader 98, arranged as-shown in Fig. .1, isfirst placed in the fuse tube unit I2; then ejector lever 68,-being pressed up against the end of the baffle wall -82, tensions the spring, the leader passing through the groove W4 around the pin #91, and being secured by means of thumb nut 104).-

A predetermined tension is thus placed upon the fuse leader 88, tending to withdraw this leader from the tube 12 as soon as the fuse melts. The explosive tendency of the melting fuse, supplemented bythe leader ejector. 68, tends to break the circuit as quickly as possibleand .-t 0 extinguish the are inside the tube 12.

The fuse tube unit I 2 having been re-fused, it is then hung upon a disconnect stick by means of the ring 84, in the inverted position; and then the fuse tube unit may be lifted by means of the stick until the lip I 12 passes over the trunniorm 62, 63; and the unit is hung on the trunnions 63 by means of the cylindrical portions H0 of the laterally projecting flanges H I.

It should be understoodthat the trunnions 6'2, 63 project laterally .from each parallel side wall 54,'55,'but terminate with a space between their ends into which the ejector lever can be inserted. The laterally projecting flanges I l l on the ejector lever project far enough to extend over the inwardly projecting trunnions. carried by :the side walls '56 so that the .ejector lever serves .at this time -asa support with which :to hang-the fuse tube unit 12 onthe lower trunnions inthe ,inverted position.

The operator then removes his disconnect stick from the ring Ba and places it in the ring Ml, which is the lowermost. The operator then uses the disconnect stick to pivot the fuse tube unit l2 counterclockwise from the inverted position to the position of Fig. 1. As the fuse tube unit !2 passes from the depending inverted position to the position of Fig. 1, it will be seen that-the laterally projecting flange i it engages the trunnions $2 and {5 3 by means of its flat surface H39. As the fuse tube unit moves upward counterclockwise from the inverted position, it will be seen that the tendency of gravity is to cause the fuse tube unit 12 to slide toward the left on the trunnions ,62, 63 due to the fact that the surface 109 will slope downward toward the left; and the trunnions 62, 53 will move into engagement with the fixed contacts H4.

When the fuse tube unit reaches the position of Fig. 1, then the fixed contacts 5 M en age the trunnions 52, 3&3 with a slight overhang of the fixed contacts i it! behind or to the left of the trunnions 62, 63, whereby the lower contacts H4 .are retained in engagement with the trunnions 62, 63.

When the upper end of the fuse tube unit 12 approaches the upper contact fixture 5 3, the cap Hi2 will be guided between theside walls of the upper hood by the flaring guide surfaces 151; and the trunnions J24 will pass under the curved surface its and along under the shoulder l ld until the trunnions we engage and compress spring .i isand snap behind the curved retaining shoulder or fixed contact m5, Then the fuse unit has beeninstalled, as shown in Fig. 1.

Operation as a disconnect To operate the assembly as a disconnect, with the parts in the position of Fig. 1, the lineman may hook the end of a disconnect stick in the upper ring Ml. By pulling on thedisconnect stick the curved upper surface of the trunnions 124 will cam the retaining shoulder or fixture contact upward, this motion being permitted by its piv- Qtal mountingon the bolt 12 Land beingresisted by the spring 127.

The shape of the parts is such that the fuse tube unit 8:2 can be pulled out Qfengagement with its upper contacts and can be lowered into the inverted position, pivoting on the lower trunnions 52, V63. The location of the parts in this position, hanging from its lower trunnions, indicates to the user that the line has been purposefully opened, using the device as a, disconnect.

The disconnect canbe closed in the same mannerasit wasclosedinthe installation of thefuse tube unit, by swinging the fuse tube unit upward counterclockwise with the disconnect stick engaging the ring ia ll until the contacts 124,145 engage .each other.

Operation as a fused drop-out cut-out When a surge of current melts the fuse .carried by the upper end ofthe fuse leader 93, the gases and nielted'partsare expelled out of the lowerend of the tube l2 and are directed by theblast chute l9 away from the face of the operator. At the same time the release of-the'tension on the fuse leader -98 permits the ejected'lever $8 to be moved byits spring in a clockwise direction, in Fig. 1, to withdraw the fuse leaderv s from the tube :12 and assure the mechanical disconnection of the leader from the cap 18.2 by pulling the leader outof the tube 12.

In this action it is advantageous to have the leader wound about the extension 91 of the ejector lever pivot, because this involves no sliding across that point of support of the leader, and thus minimizes the friction in pulling out the leader.

When the ejector lever 68 moves clockwise, on the blowing of the fuse, hammer flange I II has its sharp end moved toward the trunnions 62, 63 until the sharp end of this hammer lever engages between the trunnion and the fixed contact II4 on each side of the lower fixture 15.

This tends to raise the contacts I I4 and the entire fuse tube unit I2 sufi'iciently for the overhang of the contacts II4 to clear the trunnions 62, 63, and simultaneously urges the contacts II4 outwardly toward the right, away from the trunnions 62, 63. The fuse tube unit tends to swing by gravity also from the position of Fig. 1 to the vertical position; and thus as soon as the overhang of the contacts II4 on trunnions 62, 63 is released, the fuse tube unit I2 tends to swing to the right at its lower end in a counterclockwise direction from the position of Fig. l to a vertical position. When the fuse tube unit is in this position, it is an indication that the circuit has not been opened by using the device as a disconnect, but it has been opened by the blowing of a fuse.

Referring to Fig. 2, this figure shows a modification in which the blast chute has been omitted and the insulating tube I2 projects beyond the lower fixture. In this embodiment the ejector lever 68 has been provided with a twisted ring I64a at its outer end for passing the fuse tube leader. In this embodiment the fuse tube unit has been provided with a pry-out lever I60.

This comprises a cast metal member formed with a U-shaped yoke I6I having a pair of parallel bearing flanges I62. The bearing flanges have apertures I63 serving as bearings for rotatably mounting this pry-out lever on the upper trunnions I 24. The upper trunnions I24 may consist of a rod or pin frictionally secured in a through bore in the upper fixture, which also permits the attachment of the pry-out lever. The pry-out lever has an outwardly and upwardly curved arm I64, which is provided with a ring I65 having a circular portion I66 and a narrow portion I61. The circular portion is large enough to pass the head on a laterally projecting lug of a disconnect stick; but the narrow portion I61 of the ring is narrow enough to cause the ring to be confined behind the head on the disconnect stick.

The pry-out lever has a pair of laterally projecting lugs I68, one on each side, located to engage the spring I49, which is backed up by a second leaf spring I69. When the pry-out lever is pulled forward, the lugs I68 cam the leaf springs I49 and I69 downward to release the trunnions and cam them out of engagement with the upper contact. This pry-out lever also facilitates the removal of the tube when it is hanging down from the upper housing after fuse interruption.

It will thus be observed that we have invented a fused drop-out cut-out in which the jet action of the expelled gases will tend to push the fuse tube into engagement with its upper and its lower contacts, retarding any tendencies of the device to open too quickly. The device will not open until the power arcs are extinguished because it is only after the arc is extinguished that the jet action ceases from pressing the fuse tube unit backwardly into engagement with its contacts.

The present assembly has the contacts so arranged that they are self-aligning to compensate for discrepancies in the length of the fuse tube 12 units or in the spacing between the contact supporting arms, which are due to the variations in manufacture. The advantages of our improved device may be summarized as follows:

1. It is adapted to use standard universal fuse links of any manufacturer and to be handled according to conventional practice.

2. The lower contact of the fuse tube is ejected from the bottom contact arm upon rupture of the fuse link so that the fuse tube will hang with its opening extending downward after operation, thus protecting the interior of the fuse tube from all adverse weather conditions.

3. The construction of the mechanism is such that the mechanical opening of the lower contacts is delayed until the arc has been definitely extinguished.

4. The jet action from the lower end of the tube tends to keep the upper end of the fuse tube in its proper position and to hold the lower end in position until after the blast, thus delaying mechanical opening until the arc has been extinguished.

5. The resilient spring contacts with their wide flaring ends are adapted to register with the trurmions of the fuse tube units, even though the dimensions may vary due to manufacturing tolerances and the contacts may give sufficiently to become self-aligning as they engage the trunnions.

6. Any undue strain on the spring contacts is prevented by the provision of stop surfaces which take the thrust that is caused by jet action during rupture of a fuse.

7. The present fuse unit may be operated as a disconnect switch; but when so operated, its automatic mechanism is still trip-free so that a fault on the line will open the lower contacts, even while the operator is closing and holding the upper contacts.

8. The device gives a visual indication at all times whether it is actively in the circuit or whether the circuit has been broken purposefully at the top or automatically by rupture of a fuse at the bottom.

While we have illustrated a preferredembodiment of our invention, many modifications may be made without departing from the spirit of the invention, and we do not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of all changes within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United'States, is:

1. In a drop-out fuse cut-out, an upper contact arm structure comprising an insulating support, a metal arm carried by said support and projecting transversely from the support, a contact fixture comprising a metal member formed with a hood having a pair of substantially parallel walls joined by a top wall to close the top of said hood, said hood having an attaching flange, means for pivotally mounting said attaching flange on said arm and resilient means for urging said hood in the direction of its open side, said side walls being formed with a partially circular recessed portion in each side wall for engaging and retaining a trunnion of a fuse tube unit for pivotal movement.

2. In a drop-out fuse cut-out, an upper contact arm structure comprising an insulating support, a metal arm carried by said support and projecting transversely from the support, a contact fixture comprising a metal member formed with a hood having a pair of substantially parallel walls joined by a top wall to close the top of said hood, said hood having an attaching flange, means for pivotally mounting said attaching flange on said arm and resilient means for urging said hood in the direction of its open side, said side walls being formed with a partially circular recessed portion in each side wall for engaging and retaining a trunnion of a fuse tube unit for pivotal movement, said recessed portion covering a predetermined arc of suflicient extent to retain the trunnion when the hood is spring pressed toward said trunnion, but said hood having sufficient pivotal movement whereby it may be pivoted against said spring to move the circular recessed portion suificiently to release said trunnion.

3. In a drop-out fuse cut-out, an upper contact arm structure comprising an insulating support, a metal arm carried by said support and projecting transversely from the support, a contact fixture comprising a metal member formed with a hood having a pair of substantially parallel walls joined by a top wall to close the top of said hood, said hood having an attaching flange, means for pivotally mounting said attaching flange on said arm and resilient means for urging said hood in the direction of its open side, said side walls being formed with a partially circular recessed portion in each side wall for engaging and retaining a trunnion of a fuse tube unit for pivotal movement, said attaching flange and arm having another transverse member passing through apertures in them for limiting pivotal movement of said hood, and one of said latter apertures being enlarged to permit said pivotal movement.

4. In a contact structure for a drop-out fuse cut-out, the combination of a fuse tube unit provided at its end with a pair of trunnions, an upper contact for engagement with said trunnions, said upper contact having a hood provided with parallel side walls, and said side walls having an arcuate groove for engagement with said trunnions, and resilient means carried by said hood for urging the trunnions into said groove to retain the fuse tube unit in said hood.

5. In a contact structure for a drop-out fuse cut-out, the combination of a fuse tube unit provided at its end with a pair of trunnions, an upper contact for engagement with said trunnions, said upper contact having a hood provided with parallel side walls, and said side walls having an arcuate groove for engagement with said trunnions, and resilient means carried by said hood for urging the trunnions into said groove to retain the fuse tube unit in said hood, said resilient means comprising a leaf spring secured at one end on said hood and bowed intermediate its ends to engage said trunnions, the other end of the leaf spring having a free bearing on a part of said hood.

6. In a contact structure for a drop-out fuse cut-out, the combination of a fuse tube unit provided at its end with a pair of trunnions, an upper contact for engagement with said trunnions, said upper contact having a hood provided with parallel side walls, and said side walls having an arcuate groove for engagement with said trunnions, and resilient means carried by said hood for urging the trunnions into said groove to retain the fuse tube unit in said hood, said resilient means also serving to prevent the free swinging of said fuse tube unit on said trunnions, by engaging a fiat surface on the trunnion so located that it engages the resilient means when the fuse tube unit hangs in substantially vertical position.

'7. In a drop-out fuse cut-out, a fuse tube unit comprising an elongated insulating tube provided atits lower end with means for mounting on a contact arm, and having a metal fixture at its upper end for securing a fuse leader in said tube, said metal fixture being provided with a pair of axially aligned laterally projecting trunnions, and a pry-out lever pivotally mounted on said trunnions, said pry-out lever having an upward extension provided with an aperture for receiving the end of a disconnect stick.

8. In a drop-out fuse cut-out, a fuse tube unit comprising an elongated insulating tube provided at its lower end with means for mounting on a contact arm, and having a metal fixture at its upper end for securing a fuse leader in said tube, said metal fixture being provided with a pair of axially aligned laterally projecting trunnions, and a pry-out lever pivotally mounted on said trunnions, said pry-out lever having an upward extension provided with an aperture for receiving the end of a disconnect stick, said pryout lever being provided at its lower end with a pair of pivot flanges having apertures for receiving said aligned trunnions and one of said pivot flanges being mounted on each of said trunnions.

9. In a fuse drop-out cutout, the combination of an insulator with an upper contact arm carried thereby, said upper contact arm being provided at its forward end with a pair of downwardly open spaced grooves, a fuse tube unit provided at its upper end with a pair of axially aligned trunnions for pivotal mounting in said grooves, spring means carried by said contact arm below said grooves and extending across said grooves to urge said trunnions into said grooves to retain the fuse tube unit, and a prying pullout lever pivotally mounted on trunnions and adapted to engage said spring mean to release said trunnions from said groove upon a downward pivotal movement of said pull-out lever.

10. In a fuse drop-out cut-out, the combination of an insulator with an upper contact arm carried thereby, said upper contact arm being provided at its forward end with a pair of downwardly open spaced grooves, a fuse tube unit provided at its upper end with a pair of axially aligned trunnions for pivotal mounting in said grooves, spring means carried by said contact arm below said grooves and extending across said grooves to urge said trunnions into said grooves to retain the fuse tube unit, and a prying pullout lever (pivotally mounted on trunnions and adapted to engage said spring means to release said trunnions from said groove upon a down- Ward pivotal movement of said pull-out lever, the said pull-out lever being provided at its free end with an opening adapted to receive the end of a disconnect stick.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,549,635 Pittman Apr. 1'7, 1951 2,581,954 Hubbard et a1 Jan. 8, 1952 2,625,623 Baskerville Jan. 13, 1953 

